Method and apparatus for interurban dispatch private calling

ABSTRACT

To address the need to provide interurban dispatch services, embodiments supporting interurban dispatch private call and dispatch call alert services are disclosed. Call control in the local network equipment ( 110 - 131 ) manages the dispatch service in both the local urban area ( 101 ) and the remote urban area ( 151 ). Call flow embodiments that enable this local management of private call and call alert services across urban area boundaries are described in detail.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to a co-pending application entitled“METHOD AND APPARATUS FOR INTERURBAN DISPATCH GROUP CALLING,” filed oneven date herewith, assigned to the assignee of the instant application,and hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to communication systemsand, in particular, to interurban dispatch communication systems.

BACKGROUND OF THE INVENTION

[0003] Unlike the interconnect services provided by today's cellularsystems, dispatch services have been traditionally provided by two-wayradio systems. Such services allow a user to communicate in ways thatare difficult or costly using today's cellular systems. The dispatchgroup call service, for example, enables a user to communicate with agroup of people simultaneously and instantaneously, usually just bydepressing a push-to-talk (PTT) button. Using a cellular system, such acall could not occur instantaneously since either telephone numberswould need to be dialed for a three-way call or arrangements would needto be made to setup a conference call. A dispatch group call is idealfor a team of people who are working together as a group and often needto speak with one another spontaneously.

[0004] Likewise, the dispatch individual call service (typically aprivate call or a call alert) enables a user to communicate with anotheruser quickly and spontaneously. This feature is ideal for two people whoare working together but are unable to speak with one another directly.Where a wireless telephone call is more appropriate for a conversation,short messages between two people as they work are better facilitated bythe dispatch individual call service.

[0005] Today, Motorola's “iDEN” system provides such dispatch services,but only within limited service areas called urban areas. Thus, an“iDEN” user is currently able to make dispatch group calls and dispatchprivate calls to other users located in the same urban area. However,when one of these users leaves the urban area (travels to another city,for example) and registers in a new urban area, dispatch services withthose in the old urban area are no longer available.

[0006] Therefore, a need exists for a method and apparatus to provideinterurban dispatch services.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a block diagram depiction of a communication system inaccordance with an embodiment of the present invention.

[0008]FIG. 2 is a call flow chart illustrating messaging exchanged bysystem components in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0009] To address the need to provide interurban dispatch services,embodiments supporting interurban dispatch private call and dispatchcall alert services are disclosed. Call control in the local networkequipment manages the dispatch service in both the local urban area andthe remote urban area. Call flow embodiments that enable this localmanagement of private call and call alert services across urban areaboundaries are described in detail.

[0010] The disclosed embodiments can be more fully understood withreference to FIGS. 1 and 2. FIG. 1 is a block diagram depiction of acommunication system 100 in accordance with an embodiment of the presentinvention. System 100 comprises an “iDEN” communication system,commercially available from Motorola, Inc. of Schaumburg, Illinois,divided into constituent urban areas. Although urban areas 101 and 151are depicted in FIG. 1, the person of skill in the art will recognizethat system 100 may embody additional urban areas. Although urban areastypically refer to “iDEN” systems that provide service to distinctgeographical regions, the person of skill will also recognize that anurban area may refer to another type of system (or non-iDEN device) thatinterfaces with an otherwise “iDEN” system by supporting an interurbaninterface.

[0011] System 100 comprises “iDEN” dispatch application processors(DAPs) 110, 111, 160, and 161, which serve as dispatch controllers, andinterface to “iDEN” home location register (IHLR) 150. The DAPs alsointerface with the base sites, i.e., the “iDEN” enhanced basetransceiver systems (EBTSs) 120, 121, 170, and 171. As depicted in FIG.1, EBTSs 120, 121, 170, and 171 provide wireless service to mobilestations 140, 141, 190, and 191, respectively. However, the presentinvention is not limited to communication units that are mobile. Forexample, a communication unit may comprise a computer wirelesslyconnected to system 100 or a computer connected to system 100 via theInternet. DAPs 110, 111, 160, and 161 also interface with “iDEN”Dispatch Access Controllers (IDACs) 130, 131, 180, and 181, whichprovide system 100's interurban bearer connections between urban area101 and urban area 151.

[0012] Those skilled in the art will recognize that FIG. 1 does notdepict all of the network equipment and equipment components necessaryfor system 100 to operate. FIG. 1 only depicts a simplified diagram ofthose system entities particularly relevant to the description ofembodiments of the present invention. For example, DAPs 110, 111, 160,and 161 are each dispatch controllers, which comprise a networktransceiver and a processor, both well-known entities. Those skilled inthe art are aware of the many ways each of these entities can beimplemented and/or purchased from wireless communications companies suchas “MOTOROLA.” Processors, for example, typically comprise componentssuch as microprocessors, memory, and/or logic circuitry designed toimplement algorithms that have been expressed as computer instructionsand/or in circuitry. Furthermore, processors are known to interface withnetwork transceivers in order to communicate with other devices via datacommunication networks and/or dedicated communication links. Given analgorithm, a logic flow, or a messaging flow, those skilled in the artare aware of the many design and development techniques available toimplement a processor that performs the specified logic and communicatesvia a network transceiver as required. Moreover, those skilled in theart will recognize that the dispatch controller aspect of the presentinvention may be implemented in and across various physical componentsof system 100, not just in the DAPs.

[0013] Operation of system 100, in accordance with an embodiment of thepresent invention, occurs substantially as follows with reference toFIGS. 1 and 2. FIG. 2 is a call flow chart illustrating messagingexchanged by system components in accordance with the presentembodiment. Assume that the user of MS 140 desires to talk with the userof MS 190 using the dispatch private call service. MS 140 transmits aservice request to its serving site, EBTS 120, which routes the servicerequest to DAP 110. In one embodiment of the present invention, DAP 110is designated as the serving DAP for MS 140. Such a pre-determinedmapping of communication units to particular communication controllersis but one way of architecting interurban call processing. Certainlyother schemes may be employed instead, such as selecting a controller inreal-time based on load balancing considerations, for example.

[0014] The dispatch private call request received by the local networkequipment targets a communication unit served by remote networkequipment, i.e., MS 190. In the present embodiment, DAP 110 sends (201)a SEND_ROUTING_REQUEST message to IHLR 150 to determine what remotenetwork equipment serves target unit MS 190. To support interurbandispatch services between local and remote network equipment, the localdispatch controller coordinates with the appropriate remote dispatchcontroller to manage the dispatch service. Although the presentembodiment accesses a home location register, other embodiments mayinvolve accessing other types of databases or caches that containmobility information. MS 190 is identified in the SEND_ROUTING_REQUESTmessage using an identifier such as its Universal Fleet MemberIdentifier (UFMI).

[0015] DAP 110 receives (202) a SEND_ROUTING_RESPONSE message from IHLR150 that identifies the remote network equipment serving MS 190. It isthe network equipment of urban area 151 that serves MS 190, but in thepresent embodiment, the SEND_ROUTING_RESPONSE message indicates whichparticular DAP is the serving DAP of MS 190 (e.g., DAP 160).

[0016] DAP 110 requests the remote network equipment to page MS 190, bysending (203) DAP 160 a PC_PAGE_REQ_FWD message. In the presentembodiment, the PC_PAGE_REQ_FWD message also identifies a bearer gatewayin urban area 101 to support the dispatch private call. After receivingthe PC_PAGE_REQ_FWD message, DAP 160 pages MS 190. When MS 190 respondsto the page, DAP 160 sends (204) a PC_PAGE_RSP_FWD message to DAP 110indicating that MS 190 responded and that channel resources required tosupport the dispatch private call are available in urban area 151,specifically identifying a bearer gateway to support the call. Otherimplementations may not require MS 190 to be explicitly paged, allowingDAP 160 to respond immediately. Also, if a resource is currentlyunavailable, the call may be queued and additional messaging necessarywhen the resource becomes available.

[0017] Having received a PC_PAGE_RSP_FWD message indicating that MS 190and channel resources are available for the call, DAP 110 sends (205) aPC_START_FORWARD message requesting DAP 160 to initialize the channelresources to support the dispatch private call. Thus, both DAP 110 andDAP 160 prepare for transmission of the call. Once call setup iscomplete, e.g., the requisite wireless and interurban channelsinitialized, the private call transmission from MS 140 to MS 190 isperformed.

[0018] When MS 140 finishes transmitting, thereby completing the firsttransmit session of the call, DAP 110 receives an end-of-transmissionindication and sends (206) a PC_OPEN_CHAN_FWD message to DAP 160,indicating that MS 140 is finished transmitting. Upon receiving thePC_OPEN_CHAN_FWD message, DAP 160 notifies MS 190 that MS 140 hascompleted the transmit session.

[0019] During calls in the present embodiment, the local networkequipment performs call status checking to ensure that the local networkequipment and remote network equipment remain synchronized with respectto call states. A PC_DAP_DAP_CSC_REQ message is sent upon a timerexpiration (e.g., 45 seconds), and thus, may be sent during variousphases of a call. For example, FIG. 2 depicts a PC_DAP_DAP_CSC_REQmessage being sent (207) after MS 140 has completed its transmitsession; however, a PC_DAP_DAP_CSC_REQ message may be sent whenever acall status timer expires. The PC_DAP_DAP_CSC_REQ message indicates thepresent state of the call according to DAP 110. Possible call statesinclude “Waiting for Resources,” “Paging Target,” “Pre-Call Start,”“Originator Transmitting,” “Hang Time,” and “Target Transmitting”.

[0020] DAP 160 receives the PC_DAP_DAP_CSC_REQ message and compares themessage call state to its determination of the call state. If thereceived call state is not validated based upon DAP 160's current state,DAP 160 proceeds to teardown the call and sends an indication to DAP 110to terminate the call. Otherwise DAP 160 responds (208) to thePC_DAP_DAP_CSC_REQ message with a PC_DAP_DAP_CSC_RSP message to DAP 110indicating that the call states are synchronized.

[0021] Since MS 140 has completed its first transmit session, theprivate call is presently without a talker. For the sake ofillustration, assume that the user of MS 190 desires to talk. The userdepresses MS 190's push-to-talk button, and DAP 160, after receiving arequest to talk from MS 190, sends (209) a PC_UPDATE_REQUEST_FWD messageto DAP 110 indicating MS 190's request to talk. DAP 110 receives thePC_UPDATE_REQUEST_FWD message and determines whether talk privilegesremain unassigned. (It is possible that MS 140 has requested to talkagain, and DAP 110 has already granted talk privileges to MS 140.) Ifnot already granted, DAP 110 sends (210) a PC_CONT_FWD message to DAP160 indicating that MS 190 is granted talk privileges for a transmitsession. Upon receiving the PC_CONT_FWD message, DAP 160 notifies MS 190of its turn to transmit.

[0022] When MS 190 finishes transmitting, thereby completing the secondtransmit session of the call, DAP 160 receives an end-of-transmissionindication and sends (211) a PC_OPEN_CHAN_FWD message to DAP 110,indicating that MS 190 is finished transmitting. Upon receiving thePC_OPEN_CHAN_FWD message, DAP 110 notifies MS 140 that MS 190 hascompleted the transmit session. At this point, either MS 140 or MS 190can request to become the next transmitter. If neither MS 140 nor MS 190requests to talk for a pre-determined period of time (the “hang time” asit is referred to in dispatch), DAP 110 will send (212) aPC_ORIG_CALL_TERM message indicating to DAP 160 to terminate the call.

[0023] Instead of or in addition to using a dispatch private callservice to contact another communication unit, users may use a dispatchcall alert service or a status message service. For example, using acall alert service, a user may page another communication unit torequest a call back from that unit's user at a later time. DAP 110 mightreceive a call alert request from MS 140 targeting MS 190. DAP 110 wouldthen send (213) a CA_PAGE_REQ_FWD message to DAP 160 requesting it topage MS 190 with a call alert from MS 140. As discussed above withrespect to 201 and 202, IHLR 150 may need to be contacted to determinethe location of the target. After receiving the CA_PAGE_REQ_FWD message,DAP 160 pages MS 190 identifying MS 140 as the requesting unit. When MS190 responds to the page, DAP 160 sends (214) a CA_PAGE_RSP_FWD messageto DAP 110 indicating that MS 190 responded.

[0024] In the foregoing specification, the present invention has beendescribed with reference to specific embodiments. However, one ofordinary skill in the art will appreciate that various modifications andchanges may be made without departing from the spirit and scope of thepresent invention as set forth in the appended claims. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense, and all such modifications are intended to beincluded within the scope of the present invention. In addition, thoseof ordinary skill in the art will appreciate that the elements in thedrawings are illustrated for simplicity and clarity.

[0025] Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments of the presentinvention. However, the benefits, advantages, solutions to problems, andany element(s) that may cause or result in such benefits, advantages, orsolutions, or cause such benefits, advantages, or solutions to becomemore pronounced are not to be construed as a critical, required, oressential feature or element of any or all the claims. As used hereinand in the appended claims, the term “comprises,” “comprising,” or anyother variation thereof is intended to refer to a non-exclusiveinclusion, such that a process, method, article of manufacture, orapparatus that comprises a list of elements does not include only thoseelements in the list, but may include other elements not expresslylisted or inherent to such process, method, article of manufacture, orapparatus.

What is claimed is:
 1. A method for interurban dispatch private callingcomprising: receiving, by local network equipment, a service requesttargeting a communication unit served by remote network equipment,wherein the service request is received from an originating unit servedby the local network equipment; sending, by the local network equipment,a request for the remote network equipment to page the communicationunit; receiving, by the local network equipment from the remote networkequipment, an indication that the communication unit is available;sending, by the local network equipment, a request for the remotenetwork equipment to initialize channel resources to support the servicerequest; receiving, by local network equipment, an indication that theoriginating unit has completed a transmit session; and sending, by thelocal network equipment to the remote network equipment, an indicationthat the originating unit has completed the transmit session.
 2. Themethod of claim 1, wherein the service request comprises a dispatchprivate call request.
 3. The method of claim 1, wherein the localnetwork equipment and the remote network equipment each comprisecommunication controllers.
 4. The method of claim 3, wherein the localnetwork equipment and the remote network equipment each comprisedispatch communication controllers.
 5. The method of claim 1, whereinthe local network equipment is part of a first urban area and the remotenetwork equipment is part of a second urban area.
 6. The method of claim1 further comprising: transmitting, by the local network equipment, arouting request message to a home location register; and receiving, bythe local network equipment, a response to the routing request messagethat identifies the remote network equipment as serving thecommunication unit.
 7. The method of claim 6, wherein the communicationunit is identified in the routing request message by the Universal FleetMember Identifier (UFMI) of the communication unit.
 8. The method ofclaim 1 further comprising: receiving, by the local network equipmentfrom the remote network equipment, an indication that channel resourcesrequired to support the service request are available to the remotenetwork equipment.
 9. The method of claim 8, wherein receiving theindication that channel resources are available further comprises:receiving, by the local network equipment from the remote networkequipment, an indication of a bearer gateway in the remote networkequipment to support the service request.
 10. The method of claim 1,wherein sending the request to page the communication unit furthercomprises: sending, by the local network equipment to the remote networkequipment, an indication of a bearer gateway in the local networkequipment to support the service request.
 11. The method of claim 1further comprising: sending, by the local network equipment to theremote network equipment, an indication of a present local call state;and receiving, by the local network equipment from the remote networkequipment, an indication that a present remote call state issynchronized with the present local call state.
 12. The method of claim1 further comprising: receiving, by the local network equipment from theremote network equipment, an indication that the communication unit hasrequested to talk; determining, by the local network equipment, whethertalk privileges remain unassigned; sending, by the local networkequipment to the remote network equipment, an indication that thecommunication unit is granted talk privileges for a transmit session;and receiving, by the local network equipment from the remote networkequipment, an indication that the communication unit has completed thetransmit session.
 13. The method of claim 1 further comprising: sending,by the local network equipment to the remote network equipment, anindication to terminate support of the service request.
 14. The methodof claim 1 further comprising: receiving, by the local network equipmentfrom the remote network equipment, an indication to terminate support ofthe service request.
 15. The method of claim 1 further comprising:receiving, by local network equipment, a dispatch call alert requesttargeting a call alert unit served by remote network equipment, whereinthe dispatch call alert request is received from a call alertoriginating unit served by the local network equipment; and sending, bythe local network equipment, a request for the remote network equipmentto page the call alert unit with a call alert from the call alertoriginating unit.
 16. The method of claim 15 further comprising:receiving, by local network equipment from remote network equipment, aresponse to the dispatch call alert request.
 17. A method for interurbandispatch private calling comprising: receiving, by remote networkequipment from local network equipment, a request for the remote networkequipment to page a communication unit, wherein the communication unitis targeted by a local service request; sending, by the remote networkequipment to the local network equipment, an indication that thecommunication unit is available; receiving, from the local networkequipment, a request for the remote network equipment to initializechannel resources to support the local service request; and receiving,by the remote network equipment from the local network equipment, anindication that a service originating unit has completed a transmitsession, wherein the service originating unit is served by the localnetwork equipment.
 18. The method of claim 17 further comprising:sending, by the remote network equipment to the communication unit, anindication that the service originating unit has completed the transmitsession.
 19. The method of claim 17 further comprising: paging, by theremote network equipment, the communication unit.
 20. The method ofclaim 17 further comprising: sending, by the remote network equipment tothe local network equipment, an indication that channel resourcesrequired to support the local service request are available to theremote network equipment.
 21. The method of claim 20, wherein sendingthe indication that channel resources are available further comprises:sending, by the remote network equipment to the local network equipment,an indication of a bearer gateway in the remote network equipment tosupport the local service request.
 22. The method of claim 17, whereinreceiving the request to page the communication unit comprises:receiving, by the remote network equipment from the local networkequipment, an indication of a bearer gateway in the local networkequipment to support the local service request.
 23. The method of claim17 further comprising: receiving, by the remote network equipment fromthe communication unit, a request to talk; sending, by the remotenetwork equipment to the local network equipment, an indication that thecommunication unit has requested to talk; receiving, by the remotenetwork equipment from the local network equipment, an indication thatthe communication unit is granted talk privileges for a transmitsession; receiving, by the remote network equipment, an indication thatthe communication unit has completed a transmit session; and sending, bythe remote network equipment to the local network equipment, anindication that the communication unit has completed the transmitsession.
 24. The method of claim 17 further comprising: sending, by theremote network equipment to the local network equipment, an indicationto terminate support of the local service request.
 25. The method ofclaim 17 further comprising: receiving, by the remote network equipmentfrom the local network equipment, an indication to terminate support ofthe local service request.
 26. The method of claim 17 furthercomprising: receiving, by the remote network equipment from the localnetwork equipment, an indication of a present local call state;comparing, by the remote network equipment the present remote call stateand the present local call state; and sending, by the remote networkequipment to the local network equipment, an indication that a presentremote call state is synchronized with the present local call state. 27.The method of claim 17 further comprising: receiving, by the remotenetwork equipment from the local network equipment, a request for theremote network equipment to page a call alert unit with a call alertfrom a call alert originating unit; and paging, by the remote networkequipment, the call alert unit with a call alert from the call alertoriginating unit.
 28. The method of claim 27 further comprising:sending, by remote network equipment to local network equipment, aresponse to the request to page a call alert unit with a call alert. 29.A communication controller comprising: a network transceiver; and aprocessor adapted to perform, using the network transceiver, receiving aservice request targeting a communication unit served by remote networkequipment, wherein the service request is received from an originatingunit served by the communication controller, sending a request for theremote network equipment to page the communication unit, receiving fromthe remote network equipment an indication that the communication unitis available, sending a request for the remote network equipment toinitialize channel resources to support the service request, receivingan indication that the originating unit has completed a transmitsession, and sending to the remote network equipment an indication thatthe originating unit has completed the transmit session.
 30. Thecommunication controller of claim 29, wherein the communicationcontroller is part of a first urban area and the remote networkequipment is part of a second urban area.
 31. A communication controllercomprising: a network transceiver; and a processor adapted to perform,using the network transceiver, receiving from local network equipment arequest for the communication controller to page a communication unit,wherein the communication unit is targeted by a local service request,sending to the local network equipment an indication that thecommunication unit is available, receiving from the local networkequipment a request for the communication controller to initializechannel resources to support the local service request, receiving fromthe local network equipment an indication that a service originatingunit has completed a transmit session, wherein the service originatingunit is served by the local network equipment, and sending to thecommunication unit an indication that the service originating unit hascompleted the transmit session.
 32. The communication controller ofclaim 31, wherein the communication controller is part of a first urbanarea and the remote network equipment is part of a second urban area.